diff --git a/src/com/android/settings/deviceinfo/UsbBackend.java b/src/com/android/settings/deviceinfo/UsbBackend.java
index e648b393822..20116389b6c 100644
--- a/src/com/android/settings/deviceinfo/UsbBackend.java
+++ b/src/com/android/settings/deviceinfo/UsbBackend.java
@@ -24,6 +24,7 @@ import android.hardware.usb.UsbPort;
 import android.hardware.usb.UsbPortStatus;
 import android.os.UserHandle;
 import android.os.UserManager;
+import android.support.annotation.VisibleForTesting;
 
 public class UsbBackend {
 
@@ -41,7 +42,6 @@ public class UsbBackend {
     private final boolean mRestrictedBySystem;
     private final boolean mMidi;
 
-    private UserManager mUserManager;
     private UsbManager mUsbManager;
     private UsbPort mPort;
     private UsbPortStatus mPortStatus;
@@ -49,20 +49,26 @@ public class UsbBackend {
     private boolean mIsUnlocked;
 
     public UsbBackend(Context context) {
+        this(context, new UserRestrictionUtil(context));
+    }
+
+    @VisibleForTesting
+    UsbBackend(Context context, UserRestrictionUtil userRestrictionUtil) {
         Intent intent = context.registerReceiver(null,
                 new IntentFilter(UsbManager.ACTION_USB_STATE));
         mIsUnlocked = intent == null ?
                 false : intent.getBooleanExtra(UsbManager.USB_DATA_UNLOCKED, false);
 
-        mUserManager = UserManager.get(context);
         mUsbManager = context.getSystemService(UsbManager.class);
 
-        mRestricted = mUserManager.hasUserRestriction(UserManager.DISALLOW_USB_FILE_TRANSFER);
-        mRestrictedBySystem = mUserManager.hasBaseUserRestriction(
-                UserManager.DISALLOW_USB_FILE_TRANSFER, UserHandle.of(UserHandle.myUserId()));
+        mRestricted = userRestrictionUtil.isUsbFileTransferRestricted();
+        mRestrictedBySystem = userRestrictionUtil.isUsbFileTransferRestrictedBySystem();
         mMidi = context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_MIDI);
 
         UsbPort[] ports = mUsbManager.getPorts();
+        if (ports == null) {
+            return;
+        }
         // For now look for a connected port, in the future we should identify port in the
         // notification and pick based on that.
         final int N = ports.length;
@@ -172,4 +178,22 @@ public class UsbBackend {
         // No port, support sink modes only.
         return (mode & MODE_POWER_MASK) != MODE_POWER_SOURCE;
     }
+
+    // Wrapper class to enable testing with UserManager APIs
+    public static class UserRestrictionUtil {
+        private UserManager mUserManager;
+
+        public UserRestrictionUtil(Context context) {
+            mUserManager = UserManager.get(context);
+        }
+
+        public boolean isUsbFileTransferRestricted() {
+            return mUserManager.hasUserRestriction(UserManager.DISALLOW_USB_FILE_TRANSFER);
+        }
+
+        public boolean isUsbFileTransferRestrictedBySystem() {
+            return mUserManager.hasBaseUserRestriction(
+                UserManager.DISALLOW_USB_FILE_TRANSFER, UserHandle.of(UserHandle.myUserId()));
+        }
+    }
 }
diff --git a/tests/robotests/src/com/android/settings/deviceinfo/UsbBackendTest.java b/tests/robotests/src/com/android/settings/deviceinfo/UsbBackendTest.java
new file mode 100644
index 00000000000..99c37ef6cfa
--- /dev/null
+++ b/tests/robotests/src/com/android/settings/deviceinfo/UsbBackendTest.java
@@ -0,0 +1,60 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.settings.deviceinfo;
+
+import android.content.Context;
+import android.content.pm.PackageManager;
+import android.hardware.usb.UsbManager;
+
+import com.android.settings.SettingsRobolectricTestRunner;
+import com.android.settings.TestConfig;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.annotation.Config;
+
+import static org.mockito.Answers.RETURNS_DEEP_STUBS;
+import static org.mockito.Mockito.when;
+
+@RunWith(SettingsRobolectricTestRunner.class)
+@Config(manifest = TestConfig.MANIFEST_PATH, sdk = TestConfig.SDK_VERSION)
+public class UsbBackendTest {
+
+    @Mock(answer = RETURNS_DEEP_STUBS)
+    private Context mContext;
+    @Mock
+    private UsbManager mUsbManager;
+    @Mock
+    private UsbBackend.UserRestrictionUtil mUserRestrictionUtil;
+
+    @Before
+    public void setUp() {
+        MockitoAnnotations.initMocks(this);
+        when(mContext.getPackageManager().hasSystemFeature(PackageManager.FEATURE_MIDI))
+            .thenReturn(true);
+        when((Object)mContext.getSystemService(UsbManager.class)).thenReturn(mUsbManager);
+    }
+
+    @Test
+    public void constructor_noUsbPort_shouldNotCrash() {
+        UsbBackend usbBackend = new UsbBackend(mContext, mUserRestrictionUtil);
+        // Should not crash
+    }
+}